(1) Field of the Invention
This invention refers to a multi-computer system, and particularly to a homogeneous multi-computer system.
(2) Description of the Prior Art
Currently, parallel processing technique has been one of the main trends in the area of computer architecture and mainly takes multi-machine systems as its architecture. The aims of research and development are now focused on high speed operation and artificial intelligence, and some products have begun to be sold in markets. Being dominant in the computer market, the Von Neumann computer is still under development to increase its speed, memory capacity and other characteristics. However, the speed of the individual computer is limited by the space occupied by CPU and light speed so it is inevitable that parallel processing with multi-machine architecture will become the goal of development. Eric J. Lerner introduced some typical commercialized multi-machine system in the article "Parallel Processing Gets Down to Business", High Technology magazine in July 1985, as follows:
__________________________________________________________________________ Cycle No. of (Time) Max. Other Name Processors (n) Speed Memory Feature __________________________________________________________________________ MPP 16384 100 65 BIPS Dist. small-grain Connection 64000 1000 10 BIPS Dist. small-grain NONVON 8000 1500 16 BIPS Dist. small-grain IPSC 32-128 100 2-8 MFLOPS Dist. small-grain Butterfly 128 -- 200 MIPS shared large-grain Sigma-l 256 100 100 MFLOPS Dist. data flow Cedar 32 100 10 MFLOPS Shared data flow __________________________________________________________________________
wherein,
BIPS=10.sup.9 instructions per second PA1 MFLOP=10.sup.6 floating point instructions per second PA1 MIPS=10.sup.6 instructions per second PA1 (1) Too many troubles in the management of a multi-machine system as compared with an individual computer. PA1 (2) The software for multi-computer systems remains to be developed, and is quite different from traditional software.
From Lerner's paper and other information, it can be concluded that current research and development as well as the commercial prospects take features as follows:
A. This technology is in an expanding period; there are many concepts and designs as well as various types of classifications, but some serious difficulties.
B. High speed and artificial intelligence are being pursued and are expected to replace the supercomputers or supermini-computers.
C. Because the unit of a multi-computer system is independent, it is difficult to manage and program a multi-computer system. The number of large grain cell combination are not yet over 256.
D. Since the design of multi-machine architecture depends on the algorithm, the system is not able to be common.
E. Communication with point to point is the main way to connect between computers.
Although great efforts are made to improve the architecture of multi-machine systems, the progress achieved is lagging behind that of the individual computer. It is difficult to replace the individual computer with multi-machine system in the near future due to technical difficulties. Some papers do not consider it as a good omen (e.g. "Parallel Machines Take on Supercomputer, High technology, July 1985, p. 26) because of:
In the International Conference on Parallel Processing held in 1985, IBM announced that it was developing an RP3 machine with hypercube and shared memory (ref. to "Research Parallel Processor Prototype (RP3). Introduction Architecture" by G. F. Pitten et al., p. 264).
Electronics magazine introduced the status of Western European and Japanese efforts in two papers, "Western Europe Looks to Parallel Processing for Future Computer" (p. 114. June 1985) and "Japan is Busy Trying to Make Manufacturable Data Flow Computer" (p. 111, June 1985).
In all system architectures mentioned above, the multi-computer architecture is superior in modularity and commonality, and it is of a potential advantage at cost. The advantages are more obvious for homogeneous multi-computer system. Two typical examples of multi-computer architectures are as follows:
1. COSMIC. It was the first one using hyper-cube connection. The system consists of 2.sup.n computers each one providing n point-to-point connecting ports for communication. The system operates, in the mode of multi-instruction flow and multi-data flow (MIMD), on the basis of an algorithm of message passing. The description of this system can be found in the system IPSC manufactured by Intel Scientific Computers, Inc.
2. TRANSPUTER. It was another multi-computer system wherein each computer has three or four serial communication ports and performs communication among multicomputers at a serial speed 1 to 10 Mbit/sec. The language used is OCCAM.
Multi-computer systems have some advantages in architecture. However, they are more complex and programming of system management is more difficult. In conventional multi-computer systems, since each unit holds complete independence, the multi-computer system presented users with multiple independent instruction flows and communication connection among them. As system management, the mode of communication could merely provide weak multi-computer management capability compared with an individual computer. On the other hand, in application, the users' algorithm is restricted by the multiple instruction flows and communication to a great extend. Then only a limited amount of communication models can match with the architecture of multi-computers. Meanwhile, because the multi-computer management and the users' algorithm have to be operated on the basis of communication the multi-computer system cannot be in widespread use even though its commonality of unit is very good. In addition, a multi-computer system could not provide directly for users the usual single flow chart on the whole system.